645057756 has 180 divisors, whose sum is σ = 2011496256. Its totient is φ = 179625600.

The previous prime is 645057697. The next prime is 645057767. The reversal of 645057756 is 657750546.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 650421 + ... + 651411.

Almost surely, 2^645057756 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645057756, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1005748128).

645057756 is an abundant number, since it is smaller than the sum of its proper divisors (1366438500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645057756 is a wasteful number, since it uses less digits than its factorization.

645057756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1062 (or 1044 counting only the distinct ones).

The product of its (nonzero) digits is 882000, while the sum is 45.

The square root of 645057756 is about 25397.9872430868. The cubic root of 645057756 is about 864.0380480930.

The spelling of 645057756 in words is "six hundred forty-five million, fifty-seven thousand, seven hundred fifty-six".